Date of First Thinning in a Very High-Density Eucalyptus Plantation in the Pointe-Noire Region (Republic of Congo)

Management of the Pointe-Noire Forest requires high-performance tools for simulating tree and stand growth and assessing the sustainability of plantations. Modelling the dynamics of even-aged and mono-species stands is a very active research topic. The approaches adopted by researchers vary according to the objectives and species considered: dendrometrical, Eco physiological or architectural. Thanks to the particular nature of these plantations and the trial set-up, it will be possible to explore the various aspects of production, clearly separating the part linked to genetics (three clones tested) from the part linked to the environment (via fertilisation) and the part associated with competition between trees (via planting densities and thinning regimes). This study will make a major contribution to the applicability of the self-thinning line and the RDI (Reineke Density Index) (Reineke, 1933) to fast-growing plantations. This research work will contribute to two points: 1) product diversification, which is a way of coping with international variations in timber markets, and 2) understanding how ecosystems function in exceptionally poor conditions, which will then enable the environmental impacts of the various recommended silvicultural itineraries to be assessed. The results obtained show that competition between trees in a stand of eucalyptus at very high density (10,000 stems/ha) and in two environments of very contrasting fertility is different depending on the clone. The decision on the date of the first thinning with a view to silviculture for timber and energy wood, which aims to ensure sustained and sustainable production of eucalyptus wood in these soils, should be taken between 12 and 14 months. The competition band is strong between 14 and 17 months, when the RDI = 0.8 is double that observed at 12 months.

What Is the Impact of Ploughing on Eucalyptus Plantations in Bambou Mingali (Plateaux Batéké, Republic of Congo)?

Soil ploughing is an important stage in the preparation of planting, causing disturbance to the physical, chemical and biological properties of the soil. Soil ploughing can affect the availability of nutrients and water resources, and its effect can be short, medium or long-term. Soil ploughing accelerates surface heating and air circulation and encourages mineralisation by transforming organic matter into mineral salts, making nutrients soluble and accessible to plants. The aim of this study is to determine how soil ploughing affects the distribution of nutrients in the soil profile. The study focuses on nitrogen, carbon, phosphorus, calcium and magnesium, which are major elements of soil fertility on the Batéké plateaux in Congo. The results indicate that ploughing significantly modifies the distribution at depth des elements nutritifs: there is more accumulation at the surface than at depth (ei: nitrogen 1.34 t/ha ± 0.035 at 10 cm compared with 1.034 t/ha ± 0.098 at 50 cm) with a higher concentration of carbon (13.89 t/ha ± 0.87) followed by nitrogen (1.34 t/ha ± 0.035).

Effect of Soil Fertility and Planting Density on the Partitioning of the Above-Ground Biomass of Eucalyptus in a Plantation (Pointe-Noire, Republic of Congo)

Afforestation and reforestation are useful approaches to improve carbon sequestration. With the advent of forest plantations, growing environment conditions have become increasingly restrictive for light, soil nutrients, and interactions between trees to acquire available resources. Tree biomass data are essential for understanding the forest carbon cycle and plant adaptations to the environment. The distribution of tree biomass depends on the sum of multiple stand conditions. The data are from a dedicated experiment with two very contrasting areas of fertility, and two planting densities, including a high density at planting in order to achieve thinning. The plant material consists of the high-performance clones of Eucalyptus urophylla × E. grandis and the reference clone E. PF1. We hypothesize that the distribution of biomass changes as the intensity of competition changes and that this is accelerated by the fertility of the sites in time. The results indicate that fertilization, planting density and clones have an impact on biomass partitioning.

Diversity and Importance of Benin’s Forests and Agroforestry Systems Woody Species in Mortars and Pestles Manufacture

The disappearance of resources with high genetic potential and great utility for people and the challenge of the conservation and sustainable management of these resources are two opposing facts of which the world is now concerned. In Benin, forests and agroforestry systems complement each other in wood supply for mortar and pestle manufacture. Thus, this study aimed to investigate the diversity of woody species used for mortar and pestle manufacture and to analyze the preferences of manufacturers through an ethnobotanical approach. Based on the snowball sampling method, and interviews with 112 manufacturers from different ethnic groups, we identified 31 tree species. These species belong to 30 genera and 13 plant families. The Fabaceae are more represented with 14 species (i.e. 45% of the total). Ten are frequently used. But there are four species, such as Vitellaria paradoxa C. F. Gaertn., Prosopis africana (Guill. & Perr.) Taub., Terminalia glaucescens Planch. ex Benth. and Pericopsis laxiflora (Benth.) Meeuwen, which are highly preferred by manufacturers respectively. The calculation of the Indexes of Possession of Global Knowledge (IPSG) revealed that the ethnic group Nagot (0.204) possessed more knowledge and is followed by Mahi (0.201) and Fon (0.18) respectively. Forests and agroforestry systems are both supply sites for manufacturers. The non-parametric Wilcoxon test proved that there are no significant differences between the species’ preference for mortars or pestles manufacture (v = 181, p-value = 0.38). Since the trees cutting in agroforestry systems can be destructive to them, provisions such as the promotion of agroforestry in rural areas and the integration of the used species in the reforestations programs must be taken to curb the pressure and contribute to the conservation of the biodiversity.

Length-Weight Relationships and Condition Factors of 15 Fish Species from the Loémé River Basin (Mayombe, Republic of Congo)

Length-weight relationships and condition factors are among the commonly used parameters to link the length of a fish to its weight. The present study was initiated to find out the growth patterns and overweight status of 15 fish species in the Loémé basin in Mayombe, Republic of Congo. In the period from February 2020 to September 2021, sampling was carried out in eight stations, following a standardised capture method using four gillnets of 10, 12, 15, and 25 mm mesh size and a hawk net of 1.90 m radius with 10 mm mesh size. Length-weight relationships were calculated according to P = aLSb and the condition factor, using K = (P/LSb)* 100. A total of 1153 specimens representing 15 species, 10 genera and 6 families were recorded. The number of specimens ranged from 10 to 214 for Chrysichthys auratus and Enteromius camptacanthus, respectively. The allometry coefficient b minimum of 2.697 for Chromidotilapiamelaniae and maximum of 3.589 for Garraornata, with a mean of 3.03 ± 0.2 is significantly not different from 3 at the 0.05 probability threshold and indicates isometric growth for almost all species, except for E. camptacanthus where b = 2.858 was statistically different from 3 at the same threshold. The positive and high values of the coefficients of determination r2 = 0.787-0.989 of the species, obtained during this study, suggest that weight increases with size in the fish of the Loémé basin. The average condition factor varies from 0.524 ± 0.064 for G. ornata to 4.917 ± 0.440 for C. melaniae.

Physicochemical and Biochemical Composition of Balanites aegyptiaca Seed and Seed Oil from Burkina Faso

In Burkina Faso, the seeds of Balanites aegyptiaca have been considered to be potentially high lipid, protein and mineral sources but seem to be neglected and sometimes unknown by communities. This study aims to complete data on seed oil and detail on amino acids and minerals composition of the seed of B. aegyptiaca for better use. Physicochemical parameters such as moisture and ash content, saponification index, iodine, acid value, peroxide value and the melting point were determined. Seed oil triglycerides, fatty acids and amino acids have been estimated throughout this study. The moisture and ash content were 3.70% ± 0.1% and 2.90% ± 0.2%, respectively. The saponification and iodine values were respectively 181.96 ± 0.4 mg KOH/g of oil and 104.86 ± 0.6 g of iodine/100 g of oil. Polyunsaturated fatty acid content (50.94%) was the most important. Triglyceride (LLO, 22.4%) was the major triglyceride. 9 essential amino acids and 9 non-essential amino acids were identified. Phenylalanine (11697.82 ± 0.00 mg/kg) was the most important essential amino acid. The content of 21 minerals was determined and the most important was potassium (9323.13 ± 0.01 mg/kg). Ca/P, Ca/Mg, Ca/Mg and Na/K ratios were 0.34;1.18;0.04 and 0.19 respectively. B. aegyptiaca seed oil is a source of multiple nutritional values and can be used by the population for multipurpose.

小蠹蛀梢危害对云南松生长及抗性的影响

采用人工接种、林间调查等方法 ,研究纵坑切梢小蠹蛀梢危害对云南松生长和抗性的影响。结果表明 ,受害梢率在 2 0 .0 %以下时 ,蛀梢危害对云南松的生长和抗性无明显影响。但当受害梢率高于 2 0 .1%后 ,云南松的高、径生长随受害梢率的增加而降低 ,蛀干成功率则随受害梢率的增加而增高。

Fire temperature and residence time during dry season burning in a Sudanian savanna-woodland of West Africa with implication for seed germination

Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.

Breaking seed dormancy in Cupressus atlantica Gaussen,an endemicand threatened coniferous tree in Morocco

Cupressus atlantica Gaussen （Cupressaceae） is an endemic and endangered coniferous tree geographically restricted to the N＇Fis valley in South-Western Morocco. Like many forest species, C. atlantica exhibits dormancy which delays and reduces germination. To improve seed germination, different pre-treatments were conducted on C. atlantica seeds after storage for different periods （one, two and five years） including： scarification with sandy paper; soaking seeds in hot distilled water at 60℃ and 80℃ for 15 min and soaking seeds for 48 h in a gibberellic acid （GA3） at 1,000 and 2,000 mg·L-1. Results showed that scarification with sandy paper increased the germination rate of Atlas cypress by up to 67%, indicating that the species possess essentially an exogenous dormancy （physical dormancy） due to the hard seed coat （hardseededness）. Exogenous application of gibberellic acid （GA3） at 1,000 mg.L-1 was also effective in breaking seed dormancy and germination induction. These two treatments induced faster speed germination expressed by low number of days to first germination （8-10 days） and low values of mean germination times （MGT）. However, germination rate, under any treatment, is greatly dependent on the year of seed collection. Seeds collected in year 2004 gave the highest value, suggesting that even after five years of storage, the germination capacity of C. atlantica seeds could remain high. This observation is very interesting in the ex-situ conservation of such endemic and endangered species where the production of seeds is irregular over the years.

Comparing growth and fine root distribution in monocultures and mixed plantations of hybrid poplar and spruce

Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamifera x trichocarpa （PBT） and P. maximowiczii x balsamifera （PMB）, one improved family of Norway spruce （Picea glauca （PA）） and one improved family of white spruce （Picea abies （PG）） growing under different spacings in monocultures and mixed plots. The plantations were established in 2003 in Abitibi-Témiscamingue, Quebec, Canada, in a split plot design with spacing as the whole plot factor （1 × 1 m, 3 × 3 m and 5 × 5 m） and mixture treatments as subplot factor （pure： PBT, PMB, PA and PG, and 1：1 mixture PBT：PA, PBT：PG, PMB：PA and PMB：PG）. Results showed a beneficial effect of the hybrid poplar-spruce mixture on diameter growth for hybrid poplar clones, but not for the 5 × 5 m spacing because of the relatively young age of the plantations. Diameter growth of the spruces decreased in mixed plantings in the 1 × 1 m, while their height growth increased, resulting in similar aboveground biomass per tree across treatments. Because of the large size differences between spruces and poplars, aboveground biomass in the mixed plantings was generally less than that in pure poplar plots. Leaf nitrogen concentration for the two spruce families and hybrid poplar clone PMB was greater in mixed plots than in monocultures, while leaf nitrogen concentration of clone PBT was similar among mixture treatments. Because of its faster growth rate and greater soil resources demands, clone PMB was the only one showing an increase in leaf N with increased spacing between trees. Fine roots density was greater for both hybrid poplars than spruces. The vertical distribution of fine roots was insensitive to mixture treatment.

Exact Discrete Soliton Solutions and Periodic Solutions to (2+1)-Dimensional Toda Lattice with a New Algebraic Method

In this paper,with the aid of symbolic computation,we present a uniform method for constructing soliton solutions and periodic solutions to (2+1)-dimensional Toda lattice equation.

Effects of biochar and litter on carbon and nitrogen mineralization and soil microbial community structure in a China fir plantation

To investigate the effects of biochar addition(1 or 3%)to the soil of a China fir plantation with or without litter,we conducted a 90-day incubation experiment.We also studied the C and N dynamics and the microbial community structure of the soil.In soil without litter,the application of biochar at a rate of 3%significantly decreased CO2 emissions,while addition of 1%biochar had no effect.Biochar application did not affect the net N mineralization rate but significantly reduced the NH4?concentration after 90 days.In litter-enriched soil,biochar application had no significant effect on total CO2 emissions;however,application of 3%biochar significantly reduced the net N mineralization rate.Biochar application to soil with or without litter immediately reduced the dissolved organic carbon(DOC)concentration independent of the application rate,which was primarily due to sorption of DOC by the biochar.Phospholipid fatty acid analysis demonstrated that both concentrations of added biochar to soil(with or without litter)altered the soil microbial community structure at the end of incubation,although the effect of biochar was not as strong as the effect of time or litter application.The effect of biochar addition alone on microbial community structure was inconsistent over time.Litter added to soil significantly increased fungi and reduced Gram-positive bacteria.In the presence of litter,biochar applied at both 1%and 3%significantly increased(p<0.05)the proportion of actinomycete only at day 90.Our results indicate biochar as a potentially effective measure for C sequestration in the test soil of a China fir plantation,even in the presence of litter.

Determinations of the Configuration of C-20 in Derivatives of Adynerin Using DFT/HF Methods

The configurations of C-20 in derivatives of novel 5α-adynerin type,co-existing glycoside in pair,were identified with the calculated chemical shifts of carbon at the B3LYP/6-311＋G（2d,p）level.These glycosides are unusual cardic aglycones without the common olefin bond in ring E.

The role of net ecosystem productivity and of inventories in climate change research:the need for “net ecosystem productivity with harvest”,NEPH

Background:There is an urgent need for quantifying the terrestrial carbon sink in the context of global carbon emissions.However,neither the flux measurements,nor the national wood balances fulfil this purpose.In this discussion article we point at various shortcomings and necessary improvements of these approaches in order to achieve a true quantification of the carbon exchange of land surfaces.Results:We discuss the necessity of incorporating all lateral fluxes,but mainly the export of biomass by harvest,into the flux balance and to recognize feedbacks between management and fluxes to make flux measurements compatible with inventories.At the same time,we discuss the necessity that national reports of wood use need to fully recognize the use of wood for energy use.Both approaches of establishing an ecosystem carbon balance,fluxes and inventories,have shortcomings.Conclusions:Including harvest and feedbacks by management appears to be the main requirement for the flux approach.A better quantification of wood use for bioenergy seems a real need for integrating the national wood balances into the global carbon cycle.

Individual Leaf Area of Early Flowering Arabidopsis Genotypes Is More Affected by Drought than Late Flowering Ones: A Multi-Scale Analysis in 35 Genetically Modified Lines

Plants acclimate to drought optimizing the trade-off between biomass production and water loss while ensuring their survival and reproduction. Plants also modify their growth or phenology as complementary strategies in response to stress. Despite evidence of an interaction between flowering time and plant growth response to environmental stresses, this interaction in response to drought is under debate. To contribute to the analysis of this interaction, leaf growth of 35 genetically modified lines of Arabidopsis thaliana and their common wild-type, Col-0 was analyzed by a quantitative multi-scale phenotyping approach from cellular to whole plant scale both in well-watered and soil moderate water deficit conditions. These genotypes were selected for the various physiological functions potentially altered by their genetic modification and that could interact with plant growth and/or their drought responses. In all genotypes, leaf expansion decreased in response to drought both at the whole rosette and the individual leaf levels. Additionally, epidermal cell area and/or epidermal cell number decreased in response to the drought treatment. In contrast, the number of rosette leaves was reduced in only half of the genotypes and leaf growth duration was only modified in 4 of them. Despite long photoperiod conditions, the duration of the vegetative phase, i.e. the time elapsed between germination and flowering stage, varied from 12 to 27 days among genotypes under well watered conditions. Our analyses revealed that the differences of flowering time observed in well-watered condition impacted the leaf area response to drought. Early-flowering genotypes slightly decreased their final leaf number, but strongly reduced their individual leaf area compared with the late-flowering ones. This result underlines the difficulty to analyze plant response to environmental stresses when genotypes with different flowering dates are compared.

The design and implementation of virtual hand grasp behavior process in virtual assembly

Virtual hand is an important medium for implementation of human-computer interaction in the process of virtual assembly. And the comparability between the action of virtual hand and real man-hand has always been regarded as one of the important criteria to judge whether the virtual environment has the property of immersion. On the basis of analyzing the relative position,posture,and motion behavior relationship between virtual hand and the object to be operated during virtual assembly,this paper proposed an implementation method of combining grasp index with collision detecting technology for identifying grasp action of virtual hand. The method is to identify grasp/quit using grasp index and to implement joint angle adjustment through simulation cyclic iteration and joint angle interpolation calculation. Although some traditional method identifying the grasp action on the basis of the shape of the object is operated,the simulation result getting from virtual environment created by EON STUDIO shows that it has good features of serviceability and fidelity to realize operation control of virtual hand.

New Models for Evaluating the Adsorption Rate of an Adsorbent

Four models for the rate of adsorption in an adsorbent(slab-like,cylindrical or spherical)arepresented.The parabolic profile(PP)model is obtained by assuming a parabolic intraparticle concentrationprofile.The shell-core(SC)model is based on a shell-core type profile.The modified shell-core(MSC)medel isan extension of the SC model.And the general driving force(GDF)model is a weighted average of the PP andMSC models.Sample calculations show that the GDF model provides the best approximation.

Soil carbon and nitrogen dynamics linked to Piliostigma species in ferugino-tropical soils in the Sudano-Sahelian zone of Burkina Faso, West Africa

In the Sudano-Sahelian zone of Burkina Faso, Piliostigma reticulatum （DC） Hochst and Piliostigma thonningii （Schumach） are precursor species of fallow land colonization and they are used by rural villagers. The present study aimed to assess the contribution of Piliostigma species to soil quality improvement. We quantified organic carbon, total nitrogen, soil microbial biomass, soil basal respiration and metabolic quotient from soil samples taken under and outside Piliostigma canopies. We used one-way ANOVA to test for differences in the above parameters between locations （beneath and outside Piliostigma canopies）. We recorded increased total organic carbon under Piliostigma from 31%–105% and in total nitrogen from 23%–66%. Microbial biomass was 13%–266% higher beneath canopies as compared to outside canopies. Basal respiration was also higher beneath canopies. The chemical elements varied by class of soil texture. Metabolic quotient （qCO2） was significantly correlated to clay （r = 0.80） and silt （r = 0.79） content. Piliostigma stands produced abundant litter due to their leaf biomass. Thus, they contribute to improved total organic carbon and total nitrogen content in the different phytogeographic zones and improve soil fertility.

Tree Biomass Estimation in Central African Forests Using Allometric Models

Quantifying the tropical forests’ carbon stocks is presently an important component in the implementation of the emerging carbon credit market mechanisms. This calls for appropriate allometric equations predicting biomass which currently are scarce. In this study, we aimed to estimate above- and below-ground biomass and carbon stocks of trees, and to identify the variation in diameter-height allometry of Ipendja mixed terra firme lowland tropical forest’s trees. The study area is located at Ipendja forest management unit (UFA), close to Dongou district (Likouala Department), in Northern Republic of Congo. This study combined forest inventory data of 1340 trees recorded from eight studied plots distributed in two sites, respectively Mokelimwaekili (i.e., Old-growth forest) and Sombo (i.e., Selective logging forest). Trees measurements were done with rectangular plots, each 25 × 200 m (i.e., 0.5 ha, 5000 m2). In eight studied plots (4 plots per site), only trees with DBH ≥ 10 cm were measured and identified. 1340 trees founded were belonged 145 species and 36 botanical families (n = 733 and n = 607, for Sombo and Mokelimwaekili respectively). The analyses were conducted using allometric method for aboveground biomass (AGB) and belowground biomass (BGB) estimations. The results showed that in Ipendja forest ecosystem the mean biomass is built up for AGB (346 Mg·ha-1) as well as for BGB (81.3 Mg·ha-1), with a significant difference between forest types (F = 23.46, df = 7.771, P = 0.001). It was obvious that biomasses in Mokelimwaekili (AGB: 559.7 Mg·ha-1, BGB: 131 Mg·ha-1) were higher than those of Sombo (AGB: 291.8 Mg·ha-1, BGB: 68.5 Mg·ha-1). By this study, Ipendja forest ecosystem has clearly variations on the diameter-height relationship and biomass across the plots and the sites.

Stock and Flow of Carbon in Plant Woody Debris in Two Different Types of Natural Forests in Bateke Plateau, Central Africa

In order to know the role of plant woody debris in the carbon cycle, a study of carbon stocks and carbon flow of plant woody debris was conducted in the natural forests of the centre of the republic of Congo in the Bateke Plateau. Allometric equations were used to measure the carbon stock of in dead wood debris of Lesio-louna tropical rainforest. Three plots of 40 m × 40 m were delimited in each forest types. All plots were within 300 m of each other. The average stocks of carbon in coarse woody debris obtained are 10993 g·m-2 and 14172 g&#183m-2, respectively, in the Gallery forest (GF) and the hill-slope forest clump (HF), the difference of carbon stock between the two forests is not significant (p = 0.78). The interannual mean flow in both forests is respectively 1776 and 545 g·m-2&#183an-1 in the FG and the MSDS;this medium is not significant (p = 0.10). Carbon stocks of fine woody debris are respectively 965 and 83 g·m-2 in the GF and HF, difference is significant (p = 0.0013). The interannual mean flow of carbon in fine woody debris in the GF and the HF were respectively 310 g·m-2·an-1 and 51 g·m-2·an-1.